<blockquote class="Quote" rel="hopefully">@QQ21 ., I am traveling to Doonside, is there a train station there? If I take a cab, will it cost me that much?</blockquote>
There are trains from International Airport to Doonside but you'll need to switch trains at Central. The whole trip will take about an hour. The cab is quite pricey, as Doonside is a bit far from the airport. You can organise Uber if you have plenty of luggage to carry. Otherwise, the train is a good option and is relatively cheap. You'll need an Opal card which can be purchased just before you go inside the International Airport train station. It costs $20 (minimum) and the fare will cost around $15 minimum (the airport area is a privately managed property, hence the fare is from/to it is high). DM me if you have any questions, glad to help 🙂